Thirteen murine monoclonal antibodies have been produced against non-small cell bronchogenic carcinoma. Monoclonal antibody (MA) 503D8 reacts with adeno and large cell carcinomas of the lung, 1/2 squamous cells and 1/7 small cell carcinomas. MA24X1G9 reacts with large cell (2/12) small cell (3/3), squamous cell (2/2) and adenocarcinomas (2/2). Both antibodies react with adenocarcinomas of the breast and colon and melanoma but not with EBV-transformed B-cells, B-cell lymphomas or T-cell lymphomas. MA1H10 reacts with squamous and large cell carcinomas of the lung but not with any other carcinomas or normal cells. MA503D8 precipitates an antigen of 70,000 daltons from cell lysates which is secreted as a 150,000 dalton antigen in the supernatants of reacting cells. An enzyme-linked immunosorbent assay (ELISA) to test patient urines and sera for circulating antigen will be developed. Immunoperoxidase staining of fresh surgical specimens and washings obtained at bronchoscopy is currently underway. Additional monoclonal antibodies will be produced by using membrane preparations and membrane extracts for immunization of mice.